Ethernet controllers, in particular stand alone Ethernet Controllers, are designed to serve as an Ethernet network interface for any type of microprocessor or microcontroller. Such a controller may include a dedicated interface for the microprocessor or microcontroller such as a serial peripheral interface (SPI) bus. In some embodiments, such an Ethernet controller may also be integrated in a microcontroller. The Ethernet controller handles all communication protocols and comprises a large buffer for intermediate storage of incoming and outgoing messages. The stand alone or integrated Ethernet controller handles coordination of incoming and outgoing data packets as well as packet filtering. A microcontroller or microprocessor may communicate and control the Ethernet controller via an SPI interface or any other interface. On the Ethernet side of the controller, a stand alone Ethernet controller may have the standard twisted pair connections or so-called media dependent interface (MDI) for transmitting and receiving Ethernet protocol information. The Ethernet ports are then coupled to an RJ-45 or respective connector depending on the interface. Because receiving port or transmitting port of the external connection may be in either physical location of the RJ-45 connector, two different type of cables exist for external connection, a standard cable for straight coupling of two Ethernet cables (MDI) and a cross over cable for cross connection of two Ethernet cables (MDIX). With many standard devices, a user needs to know which cable to use.
However, many devices that comprise an Ethernet interface such as personal computers, routers, etc. comprise within the Ethernet interface a so-called autoswitch-MDIX device which allows for use of either the standard cable or the cross-over cable. The requirements for an autoswitch-MDIX functionality are standardized in IEEE 802.3-2005 Standard, Section 40.4.4. The auto-switch unit automatically detects which connection cable has been used and switches the ports accordingly. Different types of Ethernet semiconductor chips need to be used in designing Ethernet devices with and without autoswitch capabilities. Hence a manufacturer may be forced to design two different types of each device if he wants to sell different versions of a device and keep different semiconductor chips in stock for manufacturing the devices. Hence a need for a more flexible design of Ethernet semiconductor chips exists.